1. Field of the Invention
The present invention is generally related to an exhaust system for a marine engine and, more particularly, to an exhaust system that provides a catalyst device and an oxygen sensor located downstream from the catalyst device at a position away from a reversion liquid trajectory path within the exhaust system.
2. Description of the Related Art
Those skilled in the art of internal combustion engines are aware of many types of catalyst systems that are available to improve exhaust emissions emitted by the engines.
U.S. Pat. No. 4,848,082, which issued to Takahashi et al. on Jul. 18, 1989, describes an exhaust gas purifying device for a marine engine. A catalyst exhaust system for an outboard motor is described. A throttle control arrangement is incorporated for assuring rapid heating of the catalyst to its operating temperature.
U.S. Pat. No. 4,900,282, which issued to Takahashi et al. on Feb. 13, 1990, describes an exhaust gas purifying device for a marine engine. A catalytic exhaust system for a marine outboard drive is described wherein the catalyzer material is supported by a heat conductive bracket and the bracket is cooled by a cooling jacket that is supplied with coolant from the engine cooling jacket. In one embodiment, the water jacket is cooled both internally and externally by delivering water from the cooling jacket into the exhaust system to impinge upon a wall of the cooling jacket.
U.S. Pat. No. 5,133,185, which issued to Gilbreath et al. on Jul. 28, 1992, describes an anti-moisture device for engine exhaust systems. The device is intended to remove moisture droplets from an interior surface of a duct, characterized by an outer edge secured to the interior surface of the duct, an inner edge surrounding an opening, and a connecting wall between the outer edge and the inner edge. The inner edge of the anti-moisture device is positioned closer to a downstream end of the duct than the outer edge whereby the connecting wall is positioned at an angle relative to the interior surface of the duct. Moisture droplets traveling upstream will be caught between the connecting wall and the interior surface of the duct, on the downstream side of the device.
U.S. Pat. No. 5,167,934, which issued to Wolf et al. on Dec. 1, 1992, describes a catalyzer installation for boat engines and a method for catalytic exhaust gas cleaning. The invention is intended for use in boat engines and the catalyzer is subdivided into a reduction part location upstream in the exhaust gas line and an oxidation part located coaxially downstream after it. An intermediate space is located between the reduction and oxidation parts. Both catalyzer parts are surrounded by a preferably cylindrical, water cooled casing and the casing has a downstream secondary air inlet to which a secondary air blower can be connected, the secondary air separating the very hot catalyzer from the double walled, water cooled casing and, in particular, flowing around the oxidation catalyzer part in counterflow for air preheating so that the air preheating in this manner is passed through the intermediate space into the oxidation part.
U.S. Pat. No. 5,203,167, which issued to Lassanske et al. on Apr. 20, 1993, describes a marine propulsion device internal combustion engine and method for making the same. The propulsion device comprises a driveshaft housing, a propeller shaft rotatably supported by the driveshaft housing, an internal combustion engine drivingly connected to the propeller shaft, the engine including a cylinder block defining a cylinder having an exhaust port, and defining an exhaust outlet, and an exhaust passage between the exhaust port and the exhaust outlet, an exhaust catalyst apparatus mounted on the cylinder block, the apparatus including a tongue extending into the cylinder block exhaust passage and dividing the cylinder block exhaust passage into an upstream portion communicating with the exhaust port and a downstream portion communicating with the exhaust outlet. The apparatus includes an exhaust passage communicating between the upstream portion and the downstream portion. The catalyst is located in the apparatus exhaust passage.
U.S. Pat. No. 5,212,949, which issued to Shiozawa on May 25, 1993, describes an exhaust gas cleaning system for a marine propulsion unit. It is intended for use with a watercraft engine. A plurality of horizontally positioned exhaust ports are located within an engine cylinder head. An exhaust manifold communicates with each of the exhaust ports at a first end and forms a gas collecting pipe at its second end. The second end of the gas collecting pipe is positioned above the exhaust ports. A generally horizontally positioned exhaust pipe extends from the second end of the gas collecting pipe and continues in a rearward direction. Means are provided for introducing coolant from the engine into the rearwardly extending portion of the exhaust pipe.
U.S. Pat. No. 5,306,185, which issued to Lassanske et al. on Apr. 26, 1994, describes catalytic elements for marine propulsion devices. A marine propulsion device comprising a propulsion unit including a propeller shaft, a housing including an exhaust gas inlet and an exhaust gas outlet, a catalytic element supported in the housing for reorientation from a first orientation to a second orientation different from the first orientation, and structure for reorienting the element from the first orientation to the second orientation is described.
U.S. Pat. No. 5,324,217, which issued to Mineo on Jun. 28, 1994, describes an exhaust system for a small boat. It includes a water trap device for precluding water entering the exhaust system if the watercraft becomes inverted from entering the engine through the exhaust system. Coolant from the engine is delivered to a cooling jacket that encircles the entire exhaust system and is introduced into the exhaust gases downstream of the water trap so that in the event of inversion and righting the engine coolant will also not enter the exhaust system. This also provides protection for catalyzers in the exhaust system.
U.S. Pat. No. 5,408,827, which issued to Holtermann et al. on Apr. 25, 1995, describes a marine propulsion device with improved catalyst support arrangement. An internal combustion engine includes an exhaust port, an exhaust conduit communicating with the exhaust port and having an inner surface, the conduit including first and second conduit portions having respective ends, the first and second conduit portions being connected end to end, a catalyst which is located within the conduit and which includes catalytic material and a sleeve surrounding the catalytic material, wherein the sleeve has a length and an outer surface spaced from the inner surface of the conduit along substantially the entire length of the sleeve. The sleeve has a rigid, radially outwardly extending flange captured between the ends of the conduit portions, and a flexible gasket between the flange and the end of one of the conduit portions.
U.S. Pat. No. 5,425,232, which issued to Holtermann on Jun. 20, 1995, describes a marine propulsion device with means for supplying secondary air to a catalytic converter. The marine propulsion device comprises a combustion chamber, an exhaust passage, an air pump and a three-way catalytic converter. The air pump pumps air into the exhaust passage at or immediately upstream of the catalytic converter. By this construction the internal combustion engine can be run slightly rich, but the catalytic converter will see a close to stoichiometric mixture so that the pollutants in the exhaust stream can be oxidized or reduced appropriately since the catalytic converter will be able to operate as a three-way catalytic converter.
U.S. Pat. No. 5,433,634, which issued to Nakayama et al. on Jul. 18, 1995, describes an exhaust treatment for an outboard motor. The exhaust gases are normally discharged to the atmosphere at a point below the level of the body of water in which the watercraft is operating. A catalyst bed is provided in the exhaust system and the catalyst bed is protected from damage by pumping water from the exhaust conduit in response to certain conditions. These conditions may be either rapid deceleration of the engine or watercraft, stopping of the engine, or any of the combination of sensed factors. The water is pumped by a water pump which is positioned either in the outboard drive or in the hull of an associated watercraft. The pumping of water is initiated for only a predetermined time and until the sensed condition no longer is existent.
U.S. Pat. No. 6,053,785, which issued to Kato et al. on Apr. 25, 2000, describes an exhaust system and control for a marine propulsion engine. An outboard motor exhaust system and control for insuring good running and effective exhaust gas silencing and treatment is provided. The system includes a very compact exhaust system that includes an expansion chamber formed beneath the exhaust guide plate and to which the exhaust gases are delivered and removed at optimal locations. Furthermore, a feedback control employing a combustion condition sensor is employed along with a catalyst in the exhaust. Sensors are provided upstream and downstream of the catalyst to insure that it is operating at optimum conditions.
U.S. Pat. No. 6,116,022, which issued to Woodward on Sep. 12, 2000, describes a catalytic reactor for marine applications. The reactor for an internal combustion engine has a cooling jacket surrounding multiple catalyst elements. A thermal barrier layer is formed between the catalyst elements and the cooling jacket to prevent overcooling of the catalyst elements. The thermal barrier layer can be formed from insulating elements such as fibrous material, a plurality of annular rings disposed around the catalyst elements, a corrugated layer, or can be formed by an empty space.
U.S. Pat. No. 6,368,726, which issued to Holpp et al. on Apr. 9, 2002, describes a honeycomb body configuration. It includes a honeycomb body with a fluid inlet side and a fluid outlet side. The honeycomb body is formed of at least partially structured sheet metal layers which form channels through which a fluid can flow. The honeycomb body is surrounded by an inner tubular jacket and an outer tubular jacket provided concentrically in relation thereto. The inner tubular jacket is configured as a corrugated hose in at least one axial subregion thereof. The inner tubular jacket has at least one further axis subregion which lies smoothly against the honeycomb body. The corrugated subregion and the outer tubular jacket are connected at least in a longitudinal partial region of the corrugated subregion.
U.S. Pat. No. 6,639,193, which issued to Schaper on Oct. 28, 2003, describes a method and apparatus for end-surface connection of a carrier matrix of a honeycomb body by a joining technique. It relates in particular to a catalyst carrier body. The matrix is disposed in a tubular jacket and is laminated and/or wound from at least partially structured sheet metal foils or layers. The end surface of the honeycomb body is at least partially heated with the aid of a surface inductor having induction coils.
U.S. Pat. No. 6,660,235, which issued to Holpp et al. on Dec. 9, 2003, describes a catalyst carrier configuration for installation close to an engine. It includes a housing and at least one catalyst carrier body disposed in the housing. The catalyst carrier body has partition walls defining a plurality of passages for an exhaust gas. A flange surrounds the catalyst carrier body and extends radially outwards from the catalyst carrier body. The flange has a second that extends at least partially into an outer wall of the housing and can be disposed between a cylinder head and a manifold of an internal combustion engine. The catalyst carrier configuration can be mounted close to an internal combustion engine. A structural unit having at least two catalyst carrier configurations and an exhaust system are also provided.
U.S. Pat. No. 6,740,178, which issued to Kurth et al. on May 25, 2004, describes a method for producing a centered honeycomb body. The method includes forming a honeycomb body by stacking and/or winding layers of steel sheet containing chromium and aluminum resulting in the honeycomb body having channels through which a fluid can flow. The honeycomb body is introduced into a tubular jacket.
U.S. Pat. No. 6,799,422, which issued to Westerbeke et al. on Oct. 5, 2004, describes an emission control method. It is intended for use with a fixed speed internal combustion engine and includes injecting a controlled flow of air into the exhaust between a first catalyst bed adapted to reduce hydrocarbon and nitrogen oxide emissions and a second catalyst bed adapted to reduce carbon monoxide emissions.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.